The present invention relates to a porous ceramic thin film and a process for preparing the same.
Porous ceramics have been widely used for heat insulator and, recently, applied to a support of inmobilized enzyme, a carrier of catalyst and a separator. On the other hand, development of functional ceramics, particularly for a sensor has been conducted by utilizing their excellent electrical and chemical properties.
In general, a ceramic sensor exhibits its function mainly by converting chemical and electronical changes occurring on the surface of the ceramic to electric energy. Accordingly, the activity of the surface and characteristic of surface adsorption are important. For such purpose, an attempt to make the surface porous is being conducted.
However, since in conventional processes for preparing porous materials, large particles of a ceramic are simply packed to produce a bulk having large pores therebetween, it is very difficult to obtain the desired effect of the porous ceramic, i.e. activation of the surface by increasing the surface area.
An object of the present invention is to provide a process for preparing a highly functional thin film of porous ceramics by using a quite different process from conventional ones.
The process of the present invention is not involved in the conventional processes for preparing a porous material or a foamed material such as a solid phase reaction method and a melting foaming method, but concerns a process for directly preparing a thin film of a porous ceramic in the course of inorganization of an organometal compound, preferably a metal alkoxide and a hydrolysed material thereof by thermal decomposition. According to the process of the present invention a porous thin film of various kind of highly functional ceramics can be obtained.
Recently, attention has been paid to metal alkoxides which can provide very fine uniform ceramic materials by thermally decomposing the metal alkoxides directly or after being hydrolyzed. In addition, it is known that a ceramic thin film can be formed by thermally decomposing metal alkoxides after application of the solution thereof to a substrate.
In the course of studying a process for preparing a ceramic thin film from an organometal compound by adding various organic compounds to a solution of the organometal compound, the present invention has been completed from the fact that a porous ceramic thin film having unique characteristics can be obtained when a certain combination of the organometal compound and the organic compound is employed.